[rrd-users] adding DS values from multiple rrd files?

[Simon Hobson]

At 13:48 +0000 3/8/10, Joel wrote:
>Thanks guys!
>
>I think the part I'm struggling with is how to define the CDEF for 
>the "total" variable inside a php foreach loop.  I get errors about 
>the CDEF being reused.
>
>Anyone out there doing rrdtool graphing with php?

I'm working in bash script, and piping the result of a load of echo 
statements through rrdtool, but the the same principal should apply. 
The actual code I've used is :
   for direction in in out
   do
     for GraphIP in "${IPs[@]}"
     do
       [ ${GraphIP} -eq ${IPs[0]} ] \
         && echo -n "        CDEF:data${direction}avg=${GraphIP}-${direction}" \
         || echo -n ",${GraphIP}-${direction},+"
     done
     echo "
         VDEF:vdata${direction}avg=data${direction}avg,AVERAGE"
   done

The end result is I send the following to rrdtool :

CDEF:data${direction}avg=ip0-in,ip1-in,+,ip5-in,+,ip10-in,+

So I keep adding more and more terms to an RPN expression inside the 
loop. I vaguely recall it took me a long time to figure out stuff 
like this when I was first writing these graphs.

-- 
Simon Hobson

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